I don't have any experience with selectiongroups, so I checked the API and the file in sapphire/forms/SelectionGroup.php.

As far as I understand it, there is no way to display the $name of the selectiongroup right now (in your setup it would be GallerieLayout and GallerieDisplayMode). However... there is a workaround (add it above your Layout-selectiongroup and add another one above your Display-selectiongroup)